I too was rather bugged by Whitney's usage of a Nidorina rather than a third normal type, since Normals, in my opinion, are among the coolest and most underrated of Pokemon types, and when Whitney annouced that it would be a 3 on 3 battle, I remember getting all excited over which kind of normal-type pokemon her extra battler was going to be. When she tossed her first pokeball and a Nidorina popped out, I thought that it was SO anti-climax. I take Gryphon's point that it was probably intended to fit in more with Whitney's female theme than it was her preference for Normal types, but still...as an element type, Normal always got so little attention...not even their greatest representative (at the time, anyhow) was allowed to remain entirely true to them.
Personally, I'm happy that Whitney beat Ash in this one. It gave his Johto battling pattern a bit more variation if, every now and then, he got creamed upon his first attempt. Nonetheless, I would have liked to have seen Clefairy to kick a little butt before going down (even if it would have undermined Miltank's exceptional battling power somewhat), since we very rarely got to see her kind in proper combat. Granted, she got unlucky with that metronome thing, but the fact that she couldn't handle any of Cyndi's opposing attacks at all, and just wussed out and fled before things got gritty, seemed just a little too much on the pathetic side to me.